Update direct AG and single node LL threshold (#1944)

* update AG direct and single node LL threshold

* update thresholds based on MI350 expeirmental results

* disable using LL for direct AG

* enable direct AG for lower GPU counts

* direct AG single node tuning

* fix in-place buffer allocation for AG unit test

* whitespace fix

* gate direct AG for gfx950 and gfx942

---------

Co-authored-by: Nusrat Islam <nusislam@nova-login-gtu2.prov.gtu.zts.cpe.ice.amd.com>

test/common/CollectiveArgs.cpp

@@ -82,7 +82,7 @@ namespace RcclUnitTesting
         CHECK_CALL(this->inputGpu.AllocateGpuMem(this->numInputBytesAllocated, useManagedMem, userRegistered));
         this->outputGpu.Attach(this->inputGpu.U1 + (this->globalRank  * this->numOutputBytesAllocated));
       }
-      else if (this->funcType == ncclCollGather)
+      else if (this->funcType == ncclCollGather || this->funcType == ncclCollAllGather)
       {
         CHECK_CALL(this->outputGpu.AllocateGpuMem(this->numOutputBytesAllocated, useManagedMem, userRegistered));
         this->inputGpu.Attach(this->outputGpu.U1 + (this->globalRank * this->numInputBytesAllocated));